How should I format my hard drive for use on both a Mac and a PC? Is there any way I can also use Time Machine with this drive?

  • As an extension to this question - Could a Mac and PC share an external hard drive at the same time? Or would it make more sense to network them?
    – alex
    Aug 11 '09 at 8:26

Format HFS+, use as time machine. On your Windows system, install non-free MacDrive and you can read it. http://www.mediafour.com/products/macdrive/

We do this here for some of the drives that arrive to us from external vendors that are all in HFS format (and some windows people need to read it).

Or, you can just share it from your Mac over your home LAN (not exactly that useful, but..)


I use NTFS-3G for the Mac and formatted the drive NTFS. This allows me to use it on both Windows and Mac and easily move between these machines.

You can use FAT32 but it does have a file size limitation of just under 4GB (232−1 bytes).

  • 2
    As long as you do the FAT32 format from the Mac, I've been able to successfully do up to 160GB as a single FAT32 partition, and have Windows, Mac and XBox 360 successfully read/write to it.
    – John Rudy
    Jul 15 '09 at 14:09
  • 1
    FAT32 also has a file size limitation of 4GB which is killer if you're doing video editing.
    – Chealion
    Jul 15 '09 at 14:59

Formatting as FAT32 will let both your PC and your Mac read from and write to the disk. If you plan to directly connect the disk to your Mac, Time Machine will only work on it if it's formatted as an HFS+ volume (which Windows can't read without installing some third-party HFS+ driver software).

  • Well crap - thanks for the answer... just not what I wanted to hear.
    – Jeffrey
    Jul 15 '09 at 14:17

You can format it with FAT32. Although i am not 100% sure, I think you cannot use a share drive as a Time Machine target disk and still put files on there from Windows.


If the drive is big enough, consider breaking it into two partitions. The first partition as FAT32/NTFS (use the NTFS-3G driver) and the second partition as HFS+ for use with Time Machine.

Pitfall is that you have to decide how big you want each partition to be and it's a bit of a pain (though not impossible) to change once set. Though at least if you chose NTFS you could keep a copy of the driver on the HFS+ partition so you could use it with any mac.


Go with HFS+. Snow Leopard is including new Windows drivers for Boot Camp that include read & possibly write support for HFS+ volumes in Windows.

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